This invention relates to a starting device for compressors of the type comprising a PTC resistor and a protection device, both of which are inserted in a casing fitted with couplings designed for connection to the standard coupling pins present on compressors, which said device is characterised in that it also incorporates a start capacitor or a run capacitor.
In particular, the starting device in accordance with the invention comprises a box-shaped casing with teeth or the like which is designed to snap onto the compressor structure, which said box-shaped casing contains a thermal protection device, a starting device, in particular constituted by a PTC resistor, and a capacitor which may be a start capacitor or a run capacitor, as the case may be.
The casing is fitted with a connector designed for connection to the pins of the standard connectors on compressors so that the assembly can be fitted simply by connecting the device to the compressor connector, the casing being snap-fitted into its seating in such a way as to eliminate the risk of its becoming disconnected even as a result of the vibrations transmitted by the compressor motor.
In refrigerators, the motor and compressor are usually made in a single unit, enclosed in a sealed casing which is fitted with a standard three-pin connector designed for connection to the electricity supply.
Starting devices comprising means designed to supply the short-time pickup current needed to start the motor, which may be constituted by PTC resistors in the latest models, and protection devices able to cut off the power in the event of overheating or malfunction, are connected to these couplings.
Italian utility model application no. PC 98U 022, filed by the same inventor, describes a starting device that comprises a PTC resistor and a thermal switch fitted in a container with a coupling for a compressor connector on one side and terminals for connection to the power line on the other.
The invention relates to a device of this kind, characterised by the special configuration of the parts which enables a start capacitor or a run capacitor to be incorporated in the device.
According to the state of the art, when a start or run capacitor is fitted to a compressor, the capacitor is fixed outside the casing, and then connected via suitable connectors to the starting and protection devices.
Recently, starting and protection devices with a quick coupling for connection of a capacitor have also been developed, the capacitor being fitted outside the device in such a way as to project over the casing of the device.
However, this solution presents a number of drawbacks.
As a result of the vibrations generated by the compressor during operation, the capacitor, which is fitted to project over the body of the starting device, can become detached in time, with the result that means such as springs and the like designed to hold it in place are required.
This involves the additional cost of the said springs on the one hand, and the need for an additional assembly operation on the other.
Moreover, capacitors with couplings which can be rapidly connected to the body of the starting device have to be specifically manufactured, which involves a further increase in costs.
These drawbacks are solved by the present invention, which offers a starting device for compressors characterised in that it incorporates a start or run capacitor inserted directly in the casing which contains the starting and protection devices.